Conversion of hydrocarbons



March -19, 1940.

H. V. ATWELL CONVERSION 0F HYDROCARBONS v Filed Dec. 51, 195e Patented Mar. 19, i940 UNITED. STATES CONVERSION 0F HYDROCARBONS Harold V. Atwell, White Plains, N. Y., assignor to Process Management Company, Inc., `New York,

N. Y., a corporation of Delaware Application December 31,1936, Serial No. 118,539

12 Claims.

This invention relates to processes for the production of motor fuel by the cracking of relatively heavy hydrocarbon oil and by the conversion vof normally gaseous hydrocarbons and more particularly to a combination type of process involving these two general types of operation.

My invention relates in general to the aforementioned type of combination process involving the interconnection of an oil cracking unit, a thermal gas conversion unit, and a catalytic gas polymerization unit. 'I'he oil cracking unit is adapted to convert relatively heavy hydrocarbon oil, such as gas oil, to cracked gasoline with nor- 5 mally gaseous hydrocarbons having olenic constituents as a by-product. I'he thermal gas conversion unit is adapted to convert normally gaseous hydrocarbons containing both saturated and unsaturated constituents to produce high antiknock motor fuel while the catalytic gas polymerization unit polymerizes only unsaturated gaseous hydrocarbons as distinguished from the conversion of both saturated and unsaturated gases in the thermal conversion operation. The performance of a thermal gas conversion unit and a catalytic gas polymerization unit is further distinguished by the fact that in the former there is a tendency to produce a liquid product in the motor fuel boiling range having an excess of relatively low boiling componentswhereas in the latter there is a tendency to give an excess of relatively high boiling liquid polymer. ther distinction between these operations is found in the fact that'thermal polymerization effective- ;5 ly converts the lower boiling olefin, e. g., ethylene,

to liquid polymers whereas some catalytic operations have practically no effect on this hydrocarbon.

in practising my invention the products of oil =0 cracking are separated by fractionation into motor fuel and normally gaseous hydrocarbons, the

motor fuel, for the purpose of explaining my invention, being assumed to have a boiling range of 5 approximately 100 to 400 F. as determined by the A. S. T. M. method for distillation of gasoline.

The thus separated normally gaseous hydrocarbons are further fractionated to eliminate hydrogen and methane which can not be economically 0 converted to liquid products. Of the remaininggaseous hydrocarbons', a fraction consisting prerloniinantlyaof ethylene and ethane is separated `asse'cl ..to the thermal polymerization unit 1 while theslightly heavier fraction consisting pre- `5rioxni'nantly of- Ca and C =4 hydrocarbons, both sat- A fururated and unsaturated, is passed to the catalytic polymerization unit.

Products from the thermal polymerization unit are fractionated in a manner similar to products f from the oil cracking unit, this fractionation, particularly with respect to the gaseous product,

beingeected in the same or separate fractionaty ing systems.

The motor fuel fractions, or part thereof, from ihe oil cracking and thermal polymerization operations are subjected to further fractionation either separately or in a single fractionating system for the combined products to separate the motor fuel into relatively light, intermediate, and heavy fractions according to boiling point. This fractionation is effected to separate the relatively low boiling constituents which tend to be present in excess in both the thermal polymerized gasoline and in the cracked gasoline. 'Ihe relatively light and intermediate gasoline fractions, in accordance with my invention, are subjected to repolymerization in order to increase the boiling points thereof, the lightest fraction being passed preferablyto the catalytic polymerization zone while the intermediate fraction is preferably passed to the oil cracking zone. When gasoline produced in the oil cracking unit and in the thermal polymerization unit has a boiling range of 100 to 400 F., the separation thereof into the aforementioned fractions may be carried out so that the lower boiling fraction has a boiling range of approximately 100 to 150 F., with the intermediate fraction having a boiling range of approximately 150 to 200 F. Depending upon the product desired, only a portion of either of these fractions need be subjected to repolymerization as described, the balance being diverted for blending inthe final product. ,A By effecting separation in the manner abov described, a charging stock of Ca and Ct hydrocarbons containing both saturated and unsaturated constituents from the oil cracking and the .thermal polymerization units, together with more or less of the normally liquid low boiling constituents of the motor fuel produced from these units, constitutes a charging stock for the catalytic polymerization unit. In the catalytic polymerization unit, the oleiins, both normally gaseous and normally liquid, are polymerized to higher boiling products while the parafflnic components of the charge pass through the catalytic unit essentially unchanged. The products from this catalytic polymerization unit are fractionated to recover motor fuel having a boiling range of approximateiy 100 to 400 1F. and a mainly parmnic gas consisting predominantly of C3 and C4 hydrocarbons which 'may be passed to the thermal gas conversion unit where they are converted to liquid products mainly in the motor fuel boiling range. The liquid products from the catalyticy polymerization unit containing a preponderance of hydrocarbons in the upper part of its boiling range are blended with the heavy fractions of the motor fuel produced by oil cracking and by thermal gas polymerization and with any lighter components of these initial products which are not subjected to repolymerization as described.

For further understanding of my invention, reference will now be made to the accompanying drawing wherein the single figure represents a diagrammatic elevational view of apparatus suitable for carrying out my invention,

Referring to the single figure, hydrocarbon oil, auch as a clean gas oil from any suitable source, is passed through line l by pump 2 to cracking furnace 3. The cracking furnace 3 may be of the well known construction'and the oil in passing therethrough is heated to a temperature of from 850 to 1100 F. while being maintained under a pressure of from 200,to,1000 lbs. per sq. in. to effect the desired cracking thereof into lower boiling hydrocarbons. Preferably the oil is cracked under short time conditions, such as a few seconds, to produce a gasoline of high antiknock value. If desired; a reaction drum may be used to effect additional cracking of products from the furnace 3 to increase the yield of gasoline. The cracked -products from the furnace 3, or a reaction drum, if one is used, are passed through a transfer line (i having a valve 5 there-` in to an evaporator 6 which may also be provided with suitable fractionating equipment in the upper part thereof. The evaporator i5 is usually maintained at a lower pressure than that maintained on the oil passing through the furnace l, as, for example, 50 to 400 lbs. per sq. in. Tar and heavy unvaporized material of the cracked products separated in evaporator are withdrawn therefrom through a line 'l while the vaporous material of the cracked products passes overhead through a line 8 to a fractionating column 9. The fractionating column 9 may be of the well known bubble tower type provided with suitable fractionating trays or plates and separation of the insufficiently cracked products is effected therein. These insufficiently cracked products in the nature of a clean gas oil are withdrawn from the fractionating column 9 through aline l l and forced by a pump it to the inlet of the cracking furnace 3 for reprocessing in the same. cycle.

Cracked gasoline and lighter hydrocarbons pass overhead in vaporous form from the fractionator fi through line i3 and condenser lli wherein gasoline is condensed to a distillate receiver i5. Normally liquid hydrocarbons having a boiling range of about 100 to 400 F. are separated in the chamber l5 and withdrawn therefrom through line it, the normally gaseous hydrocarbons, consisting of hydrogen, methane, and the C2 to C4 hydrocarbons containing both saturated and unsaturated constituents, being conducted through line Il' to a gas fractionator i8. The normally gaseous constituents passing through line il are preferably cooled by any suitable type of heat exchanger l9 prior to entering fractionator i8 to facilitate the desired separation therein. Within the fractionator i8 the normally gaseous hydrocarbons are separated into a fraction containing mostly C3 and C4 hydrocarbons in liquefied condition which is withdrawn through a line 20 and a fraction containing hydrogen, methane, and the C2 hydrocarbons which is withdrawn through a line 2i and passed through a cooler 22 wherein it is furthern cooled, optionally with an increase in pressure, by means of a pump not shown, to facilitate separation of hydrogen and methane from the liquefied Cz fraction in fractionator 23. Hydrogen and methane thus separated may be removed from the system through a line 2H while the remaining C2 fraction, e. g., ethylene and ethane, is withdrawn through a line 25 and forced by a pump 26 to a thermal polymerization unit. The C2 fraction passing through the line 25 is admixed with other similar C2 hydrocarbons or, if desired, hydrocarbons of from two to four carbon atoms per molecule and containing both saturated and unsaturated constituents, introduced through a line 21 by pump 28, and the mixture forced into a thermal polymerization furnace 29. Thev gaseous hydrocarbons passing through the furnace 29 may be subjected to a temperature of from about '750 to 1100u F. while being maintained under a pressure of from 400 to 3000 lbs. per sq. in. to effect conversion of normally gaseous hydrocarbons into normally liquid products. If desired, the polymerized-products from the furnace 29 may be soaked in a soaking drum, not shown, to effect further conversion thereof. The polymerized products, either from the furnace 29 or from the soaking drum if one is used, pass through line 30, cooler 3l wherein they are appropriately cooled, and pressure reduction valve 32 into a fractionating column 33 provided with suitable fractionating trays or plates. 'if desired, prior or subsequent to pressure reduction on the polymerized products, a suitable quenching medium, such as liquefied gases or normally liquid hydrocarbons, may be intimately contacted with the polymerized products. The polymerized products passing through the fractionating column 23 are therein fractionated to separate material heavier than the desired motor fuel therefrom, this material in the nature of tar and gas oil being withdrawn from the system through a line 34. part or all thereof, if desired, being used as the quenching medium. The motor fuel and lighter hydrocarbon constituents, produced as a result of the thermal polymerization operation, pass overhead from the fractionator 33 through a line 35, condenser 36, and valve 3'! to another similar fractionating column 38 wherein separation between the normally liquid hydrocarbons and the normally gaseous hydrocarbons is effected. The normally gaseous hydrocarbons thus separated, containing hydrocarbons of from two to four carbon atoms per molecule and, to some extent. hydrogen and methane, pass through line 39 to line il where they join the normally gaseous hy.- drocarbons resulting from the oil cracking operation. If necessary, a pump, not shown, may be interposed in line 39 for forcing the gaseous products passing therethrough into the line I1.

Normally liquid gasoline-like hydrocarbons separated in the fractionator 38 are withdrawn therefrom through line lll and part or all of this fraction may be conducted through a line il to a subsequent fractionating system for separating the motor fuel into certain fractions. Part or all of the motor fuel Withdrawn from the chamber i5 through line i6 may be passed through line l2 to the same fractionating system, the motor fuel passing through the lines di about 200 to 400 F. is withdrawn therefromthrough' a line 46 while the lighter fraction passes overhead through a line 4l to another fractionating column 48. A suitable cooler 4l' maybe interposed in line 41 to cool the products passing therethrough to facilitate the separation being effected in tower 48. The motor fuel entering the fractionator 48 is therein separated into a fraction having a boiling range of about 150 to 200 F. and a lighter fraction, the

first mentioned or heavier fraction being with` drawn therefrom through a line 49 and forced by a *pump* 50 to the oil cracking furnace 3 wherein it is subjected to conditions eiectiveto increase its boiling point by repolymerization and improve its anti-knock. The lighter liquid fraction separated in fractionator 40 passes through line 5I and condenser 52 to separator 53 wherein a normally liquid fraction having a boiling range of from 100 to 150 F'. is separated from any gaseous constituents contained-in the motor fuel. The gaseous constituents thus separated are removed from the system through line 54 or, if desired, these constituents may be passed to the fractionator iii to recover hydrocarbons having molecular weight higher than methane therefrom. The lighter liquidfraction from the separator 53 is withdrawn therefrom through a line 55 and forced by pump 50 to a line 50 where it joins the normally gaseous hydrocarbons in liquid form withdrawn from fractionator I through line 20. The fraction withdrawn from the'fractionator i8 and the lighter normally liquid fraction withdrawn from the separator 55 pass through line 50 to heater 59 wherein they are subjected to a temperature of from 250 to 750 F. while being maintained under a pressure of from about 100 to 1000 lbs. per sq. in. -The heated products leaving the heater 50 pass through line 60 to a lcatalytic reaction chamber 6i having suitable catalysts disposed therein. Any type of catalyst may be used to effect the catalytic polymerization of the unsaturated constituents of the hydrocarbons passing therethrough, such as, for example, phosphoric acid, sulphuric acid, sodium aluminum chloride, and others. Within the catalytic reaction chamber i polymerization of the oleflns contained in the normally gaseous and normally liquid fractions is effected. While I have shown only one catalytic reaction chamber, it is to be clearly understood that more than one may be used, and if desired an entire battery thereof used, the catalyst in some being revivifled while the catalytic polymerization process is being conducted in others. 'I'he products of polymerization from the reaction chamber 6i are conducted through line 82 to an evaporator 63, preferably maintained under lower pressure. The evaporator may contain suitable fractionating plates or equivalent fractionating means whereby polymerized products heavier than the desired motor fuel may be separated, these heavier productsr being withdrawn through line 63. -Unreacted parafiinic gases and liquids, as well as polymerized olefinic constituents of these fluids, pass overhead from the chamber 63 through line 60 and cooler 34 to fractionating column 65. This overhead fraction is fractionated in fractionator 3B to effect separation between the motor fuel constituents contained therein and lighter, the motor fuel constituents, having a boiling range of 100 to 400 F., being Vwithdrawn through a line 66; Unreactednormally gaseous paramns separated in the fractionator 65 pass through line 61 and 'cooler 68.110 a separator 69 wherein separation between the Ca and C4 parafiin's and lighter, if any, is effected, any lighter paramnic hydrocarbons being withdrawn from the system through a line 1i. If desired, the gases passing through line .1I may be conducted to fractionator i8 for further treatment as described. The separated C3 and C4 paraiiinic hydrocarbons are withdrawn from the separator 69 through a line 12 .and forced by a pump 'I3 to the thermal polymerization furnace 20 wherein they are subjected to polymerization conditions of temperature and pressure to effect conversion thereof motor fuel boiling range.

` It may not be desirable in some instances to separate all of the motor fuel obtained from cracking hydrocarbon oil and that obtained from the thermal polymerization of the gases into various fractions for repolymerization. In accordance with this aspect of my invention. part or all of the motor fuel, withdrawn from separator i5 through line I6 may be conducted through line 14, and part or all of the motor fuel withdrawn from fractionator 38 through line 40 may be conducted through line 15, to a manifold il wherein the motor fuels are blended. Moreover, the fraction of the motor fuel boiling between 200 and 400 F. and separated in fractionator 4,5 may be passed through the line 40 to the manifold l1 for blending with the aforementioned motor fuels. Furthermore, if it is not ldesired to repolymerize all of the fraction boiling between 150 and 200 F. and withdrawn from the fractionator 48 through line 40, apart thereof may be passed through line 10 to manifold 1l for blending with the fraction having a boiling range between 200 and 400 F., and similarly a part of the fraction having a boiling range of between 100 and 150 F., and withdrawn into normaly'I liquid hydrocarbons within the from the separator 53 through line 55, may be passed through line 18 for admixture with the motor fuel constituents passing therethrough.

As a modification of my invention, part of the Ca to C4 normally gaseous hydrocarbons withdrawn from fractionator i0 and passing through line 20 may be by-passed through line 82 for admixture with part or' all of the relatively light normally liquid fraction passing through line to extension line Bi. The mixed C: and'C4 hydrocarbonsl and the lighter normally liquid hydrocarbons, in accordance with this modication,

may be passed through line 83 to the thermal.

' plished. For example, a single fractionator may be provided in lieu of fractionators 33 and 38 or fractionatorsf 45 and 40. Each of the various fractionators/may be provided with suitable refluxing medium' introduced in a well known manner as well as cooling coils in the top and heating coils in the bottom thereof, if desired. 4More "rated constituents into a fraction predominating.

over, instead of fractionating the gaseous hydrocarbons as described, an absorption system, well understood, may be used instead of the fractionators iB and 23.

Obviously, manymodications of my invention may be made Without departing from the spirit and scope thereof as appearing hereinafter` in the appended claims.

I claim:

l. In the manufacture of normally liquid hydrocarbons from normally gaseous hydrocarbons, the process that comprises separating normally gaseous hydrocarbons containing saturated and unsaturated constituents into a fraction predominating in C2 hydrocarbons and another fraction predominating in higher boiling normally gaseous hydrocarbons, separately subjecting each of said fractions to conversion conditions to convert at least some of the normally gaseous hydrocarbons to normally liquid gasoline-like hydrocarbons, separating low-boiling normally liquid constituents boiling below about 200 F. from raid normally liquid gasoline-like hydrocarbons, and admixing low-boiling normally liquid constituents thus separatedI with at least one of the normally gaseous fractions undergoing conversion.

2. In the manufacture of normally liquid hydrocarbons from normally gaseous hydrocarbons, the process that comprises separating normally gaseous hydrocarbons containing saturated and unsaturated constituents into a fraction predominating in C2 hydrocarbons and another fraction predominating in higher boiling normally gaseous hydrocarbons, separately subjecting each of said fractions to conversion conditions to convert at least some of the normally gaseous hydrocarbons to normally liquid gasoline-like hydrocarbons, separating the normally liquid gasoline-like hydrocarbons from the products resulting from the conversion of said normally gaseous fractions, separating low-boiling normally liquid constituents boiling below about 200 F. from said normally liquid gasoline-like hydrocarbons, and admixingjlow-boiling normally liquid constituents thus separated with at least one of the normally gaseous fractions undergoing conversion.

3. In the manufactureof normally liquid hydrocarbons from normally gaseous hydrocarbons, the process that comprises separating normally gaseous hydrocarbons containing saturated and unsaturated constituents into a fraction predominating in C2,hydrocarbons and another fraction predomnating in higher boiling'normally gaseous hydrocarbons, separately subjecting each of said fractions to conversion conditions to convert at least some of the normally gaseous hydrocarbons to normally liquid gasoline-like hydrocarbons, fractionating the products resulting from the conversion of the fraction predominating in C2 hydrocarbons to separate therefrom low-boiling normally liquid constituents boiling below about 200 F., and admixing low-boiling normally liquid constituents thus separated with at least one of the normally gaseous fractions undergoing conversion.

4. In the manufacture of normally liquid hydrocarbons from normally gaseous hydrocarbons, the process which comprises separating gaseous hydrocarbons containing saturated and unsatuh'ydrocarbons and another fraction predoninating -'in higher boiling normally gaseous hydrocarbons, subjecting the fraction predominatirig in C2 hydrocarbons to ,thermal conversion conditions to eect conversion of normally gaseous hydrocarbons to normally liquidgasoline-like hydrocarbons, subjecting the fraction predominating in higher boiling normally gaseous hydrocarbons to catalytic conversion conditions to effect I conversion of normally gaseous hydrocarbons to lfraction undergoing thermal conversion.

5. The method of producingpgasoline motor fuel which comprises subjecting normally liquid hydrocarbons higher boiling than gasoline to cracking conditions of temperature and pressure to effect conversion thereof to gasoline-like hydrocarbons and normally gaseous hydrocarbons, subjecting normally gaseous hydrocarbons thus produced having more than one carbon atom per molecule to polymerizing conditions of tempera.- K

ture and pressure to effect conversion thereof to gasoline-like hydrocarbons, separating from gasoline-like hydrocarbons thus produced a light gasoline fraction containing in substantial proportion the normally liquid light ends of gasoline and an intermediate gasoline fraction higher boiling than said light gasoline fraction and substantially free of the heavy ends of gasoline, admixing said light gasoline fraction with said normally gaseous hydrocarbons undergoing polymerizing treatment, and admixing said intermediate gasoline fraction with said normally liquid hydrocarbons undergoing cracking treatment.

6. The method in accordance with claim 5 wherein said light gasoline fraction is recovered at least in part from the products of said cracking treatment.

7. The method in accordance with claim 5 wherein said light gasoline fraction is recovered at least in part from the products of said polymerizing treatment.

8. The method in' accordance with claim 5 wherein said polymerizing treatment is carried out under thermal conditions in the absence of catalytic material.

9. The method in accordance with claim 5 wherein said polymeriging treatment is carried out in the presence of a polymerizing catalyst.

10. The method of producing gasoline motor fuel which comprises subjecting normally liquid hydrocarbons higher boiling than gasoline to cracking conditions of temperature and pressure to effect conversion thereof to gasoline-like hydrocarbons and normally gaseous hydrocarbons, separating from said normally gaseous hydrocarbons a fraction predominating in C2 hydrocarbons and a fraction predominating in higher boiling normally gaseous hydrocarbons, separately subjecting each of said fractions to polymerizing conditions to convert at least a. portion thereof to gasoline-like hydrocarbons, separating from the products of said cracking treatment a light gasoline fraction containing in substantial proportion the normally liquid light ends of gasoline, and admixing said light gasoline fraction with said C2 fraction undergoing polymerizing treatment.

11. The method of producing gasoline `motor fuel which comprises subjecting normally liquid hydrocarbons higher boiling than gasoline to cracking conditions of temperature and pressure to eiect conversion thereof to gasoline-like hydrocarbons and normally gaseous hydrocarbons, separating from said normally gaseous hydrocarbons a fraction predominating in C2 hydrocarbons anda fraction predominating in higher boiling normally gaseous hydrocarbons, separately subjecting eachof said fractions to polymerizing conditions to convert at least a portion thereof to gasoline-like hydrocarbons, separating from the products of said cracking treatment a` light gasoline fraction containing in substantial proportion the normally liquid light ends of gasoline, and admixingsaid light gasoline fraction lwith said higher boiling normally gaseous hydrocarbon fraction undergoing polymerizing 4treatment.

12. The method of producing gasoline motor fuel which comprises separating normally gaseous hydrocarbons into a fraction predominating in C2 hydrocarbons and a higher boiling fraction, subjecting said C2 fraction to elevated conditions of temperature and pressure to effect conversion thereof to gasoline-like hydrocarbons, separately subjecting said higher boiling normally gaseous fraction to polymerizing conditions of temperature and pressure in the presence lof a polymerizing catalyst to effect conversion thereof into gasoline-like hydrocarbons, separating from the products of the thermalconversion treatment of said C2 fraction a light gasoline fraction containing in substantial proportion the normally liquid light ends of gasoline, and admixing said light gasoline fraction with said higherboiling normally gaseous fraction undergoing catalytic polymerizing treatment.

`HAROLD V. ATWELL. 

